| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an omnidirectional antenna for RFID, capable of reading the throughout the periphery of the antenna, without having to depend on the polarization of an IC tag. <P>SOLUTION: A cylindrical case 12 is provided on a base 11, and for example, a first vertically polarized omnidirectional antenna element 13 and a second horizontally polarized omnidirectional antenna element 14 are provided on a single axis, with a center gap of about λ/2 in the cylindrical case 12. A feed part 15 of the first antenna element 13 and a feed part 24 of the second antenna element 14 are fed from an RFID reader/writer 31 via a phase controller 33 and feed cables 32a and 32b. The RFID reader/writer 31 temporally changes the feed phase difference for the first antenna element 13 and the second antenna element 14 by a phase controller 33 to control the radiation direction of a circularly polarized wave. <P>COPYRIGHT: (C)2009,JPO&INPIT |
